Analysis Of Fluid-Solid Coupled Heat Transfer Considering Boiling Effect Of A Cooling System

The engine cooling system is to make the engine work in appropriate temperature. The low or high engine operating temperature will affect it work. In the water jacket, the cooling water flow’s velocity and state may reduce the cooling effect, and affect the utilization of heat energy and the distribution of the heat loading parts.The precondition for thermal fatigue investigation of cylinder head is to study the heat transfer in cooling water jacket. Boiling heat transfer is one of the most important heat exchange modes in water jacket. The analysis of the boiling heat transfer coefficient and the researching heat transfer of the cooling system can more accurately evaluate and design cooling jacket. Boiling heat transfer used rationally and effectively can not only enhance the engine cooling effect and distribute the temperature more uniformly, but also can increase the emission efficiency, lessen fuel consumption ratio and economize the costing of engine.This article uses the FEA and CFD software for a16cylinders diesel engine cooling water system to be simulated. Firstly, I properly mesh the cooling water jacket model, and calculate it, to get more accurate results. I select the smallest cooling water flow rate cylinder, and mesh the cylinder for the better quality of grid, then input boundary conditions of import and export for a more effective analysis of the flow field. Analysis of the results, shows that the lowest average flow velocity cylinder is8cylinder that has weaker cooling effect. I create a coupled heat transfer model which was made up of cooling water jacket, cylinder head and cylinder liner. In order to investigate the impact of boiling on the heat transfer in coupled model, fluid-solid coupled numerical simulation on the flow and heat transfer of coupled model of the engine were conducted respectively using the single-phase flow convective heat transfer model in CFD software when not considering boiling and the homogenous flow boiling heat transfer model built in this paper when considering boiling. The calculation results show that the numerical results of the homogenous flow boiling heat transfer model are more close to the experimental results, indicating that considering boiling heat transfer is more in line with the actual situation of flow and heat transfer in cooling water jacket.